Method and apparatus for repairing a photomask

ABSTRACT

A method and apparatus for correcting phase shift defects in a photomask is provided by scanning the photomask for the defect and determining locations of at least one defect. Following the determination of the location of a defect, the defect is three-dimensionally analyzed producing three-dimensional results. Utilizing the three-dimensional results, a focus ion beam (FIB) is directed onto the defect to eliminate the defect. The FIB is controlled by an etch map which is generated based on the three-dimensional results. To provide further precision to the repairing of the photomask, test patterns of the FIB are generated and three-dimensionally analyzed. The three-dimensional test pattern results are further utilized in generating the etch map to provide greater control to the FIB.

This is a continuation of application Ser. No. 09/514,823 filed Feb. 28,2000 now U.S. Pat. No. 6,322,935.

FILED OF THE INVENTION

The present invention relates generally to a method for correctingdefects formed on a photomask, more specifically, to a method forcorrecting defects formed on a alternating phase shift photomask.

BACKGROUND OF THE INVENTION

The attempt to increase integration density of semiconductor circuitshas resulted in the significant size reduction of patterns used to formthe semiconductor circuits. Photomasks are utilized by the semiconductorcircuit industry to produce the minute patterns onto semiconductormaterials or wafers through photolithographic processing during themanufacturing of these integrated semiconductor circuits.

FIG. 1 depicts a sectional view of a portion of a standard photomask 52.Referring to FIG. 1, a typical mask has a metal light shielding film orlayer 54 of a prescribed pattern formed on a mask substrate 56. When themetal light shielding film 54 is formed through known techniques anopaque defect (excess metal film) 72 may be generated. FIGS. 2-4illustrate one example the generation of an opaque defect 72 on a mask52 in the manufacturing process of a standard mask 52. FIG. 2 depictsone of the initial stages in the generation of a mask 52. A layer oflight shielding film 54 is disposed over the entire surface of masksubstrate 56. Mask substrate is normally formed of a transparent silica,quartz or other material well known in the art. Light shielding film 54is typically formed of elements and compounds consisting of Cr, Mo, F,Si, Zr, O, N. A layer of photo sensitive polymer resist 58 is depositedover the entire surface of layer of light shielding film 54. Afterresist 58 is coated over the metal light shielding layer 54, aprescribed portion of resist 58 is exposed to a radiation source 64. Ifforeign material 66 is present in or on resist 58 at the time ofexposure, in a region of mask 52 to be exposed, the portion of resistpositioned under foreign material 66 will not be exposed resulting in amask defect. Referring to FIG. 3, if the region to be originally exposedis thus not exposed due to foreign material 66, unnecessary resistartifacts 68 are formed when resist 58 is developed. Referring to FIG.4, when unnecessary resist artifact 68 is formed, and the metal lightshielding film 54 is subjected to etching, utilizing resist 58 as anetching pattern, a metal light shielding film opaque defect 72 isformed. Alternatively, due to incorrect exposure or an error in thedesign pattern, other areas of resist 58 also may not be exposedresulting in similar defects in mask 52. FIG. 5 depicts a standardmethod to correct opaque defects 72 in metal light shielding film 54utilizing an Nd:YAG laser beam or alternatively a focus ion beam (FIB)74. FIB 74 is irradiated onto opaque defect 72. Thus, opaque defect 72is evaporated or sputtered and removed, as shown in FIG. 6. An Nd:YAGlaser beam typically used has a wavelength of about ˜532 nm andirradiated for about 200 mJ-300 mJ, while a typical FIB 74 uses a doseof approximately 400-600 μJ.

The prior art methods for correcting the opaque defect 72 of metal lightshielding material have provided satisfactory results in correctingopaque defects 72 in standard masks. However, when using a laser toremove the metal light shielding material, the metal light shieldingmaterial is not removed, but is displaced or redeposited in thesurrounding areas causing material swelling in the mask. Additionally,the laser spot size is large, thus, limiting the ability to repairhighly integrated patterns. Further, the use of lasers tends to remove aportion of the substrate under the defect depending on the defect size.Because of the heat required to ablate the opaque defect 72 of lightshielding material, the underlying substrate 56 is usually partiallyablated or melted through thermal conduction, thus, reducing theeffectiveness and precision of mask 52.

The effectiveness of an FIB 74 in the removal of opaque defect 72 is, toa large extent, based on the fact that a contrast distinction existsbetween the defect 72 and the transmitting window 78. Because FIBdevices utilize secondary charged particles for imaging (i.e. secondaryelectrons or ions), a contrast between the defect and the correctlyetched areas must be present to properly determine the size of thedefect and the amount of light shielding material to be removed. With astandard mask 52, the contrast is large, the defect consists of a metallight shielding material while the correctly etched area is atransparent material. Thus, an FIB device can determine the size andamount of correction. However, without a significant contrast, an FIBdevice would not be able to accurately determine the defect size nor thedegree of correction needed to accurately correct the defect or to avoidfurther damage to the surrounding mask.

The need to increase integration density has forced the positioning ofthe light transmitting windows or regions 76 a and 76 b closer together,as shown in FIG. 7. However, light transmitted through transmittingwindows 76 will overlap if transmitting windows are positioned too closetogether. The light intensity 78 of the light transmitted throughtransmitting windows 76 a and 76 b is shown in FIG. 8. Light intensity78 a transmitted through window 76 a will overlap light intensity 78 btransmitted through window 76 b. Thus, a total light intensity 80results producing an in inaccurate integrated circuit.

In order to achieve further increased integration density a photomaskingtechnique has been developed which provides for an alternating phaseshift in the light which is projected through the mask. This type ofphotomasking is known as alternating phase shift photomasking orLevenson phase shift masking.

FIG. 9 depicts a sectional view of a portion of an alternating phaseshift photomask or Levenson phase shift mask 120. Phase shift mask 120includes a transparent silica substrate 122, including a phase shiftregion or layer 124 formed in substrate 122, and a radiation shieldingfilm 126. For simplicity, this specification assumes the radiation usedto form an integrated circuit pattern is light, although other types ofradiation are also suitable. When radiation, for example from a lightsource, is shown or exposed onto mask 120, light passes through theregions of mask 120 which are not covered by light shielding film 126.The light which passes through mask 120 will be affected by the phaseshift layer 124. Because of differing heights of phase shift layer 124,the light passing through it will exit mask 120 with different phases.The transparent regions or phase shift areas 130 a and 130 b arespecifically arranged in an alternating pattern such that a first phaseshift layer thickness (for example at 130 a) is positioned next to asecond phase shift layer thickness (130 b) such that light passingthrough transparent regions 130 a and 130 b will exit at alternatingphases thus producing a cancelling effect. The height differences of thephase shift layer 124 are specifically calculated according to theexposure lambda (λ) and index of refraction (n) of the substrate stepdepth (d), defined by: d=Φ/πλ/(n−1).

In FIG. 10, the electric field of the transmitted light passing throughmask 120 is shown. The light transmitted through region 130 a of mask120 produces a negative electric field 142 due to the lack of phaseshift layer 124. The light transmitted through region 130 b of mask 120,and thus phase shift layer 124, results in a positive electric field 144and is thus 180° out of phase with the light transmitted through region130 a.

Due to the placement of the alternating transparent regions, the lighttransmitting through transparent regions 130 a and 130 b will produce acancelling or destructive interference on those regions between thetransparent regions 130 a and 130 b. Thus the exposure resolution anddepth is greatly improved. FIG. 11 depicts the resulting transmittedlight intensity of the light being transmitted through mask 120. Becauseof the cancelling effects of the alternate phases, the light intensityis ideally at a zero level 148 between transparent regions 130 a and 130b, and at a maximum positive level 150 a and 150 b at the transparentregions 130 a and 130 b.

When the substrate etching process to form a phase shift photomask isperformed, any foreign material in the photo resist or on the substratewill produce a defect in the mask. The foreign material will interferewith the etching process thus producing an unetched bump or incompleteetching in phase shift layer 124. These defects are three-dimensional innature. Use of a laser beam cannot remove the phase shift defect,because the phase shift defect is formed of a transparent material likeSiO₂, and a laser beam will transmit directly through the phase shiftdefect, thus having no effect on the phase shift defect. Further, alaser would not provide the accuracy needed because the laser spot sizeis so large in comparison to the size of both the mask details anddefects.

Defects within a mask make the mask virtually useless, thus drasticallyincreasing the costs to manufacture integrated circuits. Due to theextreme accuracy needed in the manufacture of Levenson phase shift masksand the size of the defects created, simply directing an FIB onto aphase shift defect cannot accurately correct the defects. Because thedefect and the substrate are the same material, there is no contrast todistinguish the defect from the substrate. Thus, the FIB cannotaccurately determine the size of the defect nor the amount of correctionneeded. Further, because the FIB device cannot determine size, locationand amount of correction needed, the FIB can cause extensive damage tothe substrate or surrounding phase shift material. Therefore, aneffective and accurate method of correcting phase shift defects isneeded.

SUMMARY

A method and apparatus for correcting phase shift defects in a photomaskis provided by scanning the photomask for the defect and determininglocations of at least one defect. Following the determination of thelocation of a defect, the defect is three-dimensionally analyzedproducing three-dimensional results. Utilizing the three-dimensionalresults, a focus ion beam (FIB) is directed onto the defect to eliminatethe defect. The FIB is controlled by an etch map which is generatedbased on the three-dimensional results. To provide further precision tothe repairing of the photomask, test patterns of the FIB are generatedand three-dimensionally analyzed. The three-dimensional test patternresults are further utilized in generating the etch map to providegreater control to the FIB.

The method and apparatus of the present invention provide for theprecise removal of residual phase shift defects. Because the defects arethree-dimensional, simply directing an FIB at the defect will notaccurately remove the defect. By providing a three-dimensional analysisof the defect, the present invention provides for greater precision incorrecting the defect and thus produces a much more highly accuratealternating phase shift photomask. Further, by providing for theanalysis of test patterns of the beam being utilized to correct thedefect, even greater precision is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a portion of a standard prior artphotomask.

FIG. 2 is a cross-sectional view of a portion of a prior art photomaskduring one phase of an etching process including photo resist material.

FIG. 3 is a cross-sectional view of the prior art photomask of FIG. 2after an etching including foreign material and resist artifact.

FIG. 4 is a cross-sectional view of the prior art photomask of FIG. 3after resist material has been removed including opaque defect.

FIG. 5 is a cross-sectional view of the prior art photomask of FIG. 4including a focus ion beam being directed onto the opaque defect.

FIG. 6 is a cross-sectional view of the prior art photomask of FIG. 5after opaque defect has been removed.

FIG. 7 is a cross-sectional view of a prior art photomask including two,closely spaced, transmitting windows.

FIG. 8 is a graphical representation of the light intensity transmittedthrough the prior art photomask of FIG. 7.

FIG. 9 is a cross-sectional view of a portion of a prior art alternatingphase shift photomask including light transmitting or phase shift areas.

FIG. 10 is a graphical representation of the electric field intensity oflight transmitted through phase shift areas of the prior art photomaskof FIG. 9.

FIG. 11 is a graphical representation of the light intensity transmittedthrough the prior art phase shift mask of FIG. 9.

FIG. 12 is a cross-sectional view of a portion of a photomask includinga bump defect.

FIG. 13 is a cross-sectional view of a portion of a photomask includingan incomplete etching defect.

FIG. 14 is a two-dimensional graphical representation of the incompleteetching defect of FIG. 13.

FIG. 15 is a three-dimensional graphical representation of theincomplete etching defect of FIG. 13.

FIG. 16 is a graphical representation of an etch map of the incompleteetching defect of FIG. 13.

FIG. 17 is a cross-sectional view of a test substrate material includingtwo test patterns.

FIG. 18 is a cross-sectional view of the test substrate as shown in FIG.17 including parameter measurements.

FIG. 19 is a cross-sectional view of a portion of a repaired phase shiftphotomask after a defect has been removed.

FIG. 20 is a flow chart representing one embodiment of the method ofrepairing a phase shift photomask.

FIG. 21 depicts a schematic block diagram of the apparatus of thepresent invention utilized to repair alternating phase shift masks.

DETAILED DESCRIPTION

The present invention provides a novel method and structure for thecorrection of errors or defects on Levenson or alternating phase shiftmasks. FIG. 9 depicts one embodiment of a Levenson phase shift mask 120.Phase shift mask 120 includes a mask substrate 122 formed from anysuitable material which is transparent, rigid, thermally stable (lowthermal expansion) and durable, including silica, quartz, calciumfluoride (CaF₂) and other materials well known in the art. Substrate 122includes a phase shift region or layer 124 formed in substrate 122 byetching substrate to create phase shift differential step heights 132. Alight shielding layer or film 126 is formed over predefined regions ofphase shift layer 124 and substrate 122. Light shielding layer 126 isconstructed of any suitable material which blocks all or some portion oflight or radiation, including metal such as chromium (Cr), metalcompounds such as molybdenum silicide (MoSi), chromium fluoride (CrF)and chromium oxide (Cr_(m)O_(n), where m≧1, n≧1), and other lightshielding material as are well known in the art.

In forming phase shift mask 120 a predefined pattern is etched intolight shielding film 126, for example through well known techniques,thus exposing phase shift layer 124. Phase shift areas 130 a and 130 bare then formed by a second etching which creates the phase differentialstep heights 132 a and 132 b in phase shift layer 124 of substrate 122.The second etching is performed by a similar process as the etching ofthe light shielding film 125. A resist is distributed over mask 120 anda pattern exposed in the regions where a phase shift step height 132 ais desired. The etching is performed in any convenient manner, includingby etching processes well known in the art, for example an anisotropicplasma etching of fluorinated chemistry. The resist is then removedresulting in a mask with phase differential step heights 132. Thesephase differential heights 132 a and 132 b provide for the alternatingphase which is produced as light or other form of radiation is exposedonto mask 120 and passes through phase shift areas 130 a and 130 b.FIGS. 12 and 13 show two types of phase shift defects 146 a and 146 b.Phase shift defects 146 a and 146 b formed in the phase shift areas 130a and 130 b severely affect the accuracy of mask 120. Therefore, it iscritical to the mask production process that defects 146 a and 146 b arefound and corrected. When phase shift defects 146 a and 146 b aredetected it is necessary to remove and planarize the surfaces of defects146 to ensure an accurate mask.

The novel invention disclosed herein provides for the correction of maskdefects which greatly reduces the cost of mask production, provides forincreased accuracy in the integrated circuits produced, and provides foran overall reduction in total cost in the production of highlyintegrated circuits. In one embodiment of the present invention,following the etching of the phase shift masks 120 as is know in theart, mask 120 is then inspected for defects. One device which is usedfor inspecting mask 120 includes the use of an appearance tester (notshown), manufactured by KLA Instruments Corp. of San Jose, Calif., orother similar devices known in the art can be used. The appearancetester operates by comparing the mask image to the mask design stored inmemory within or external to the appearance tester, or by comparing onedie to another. During inspection of mask 120, if defects are detectedin phase shift layer 124, the exact locations of the defects found bythe appearance tester are stored.

Two examples of etched phase shift defects 146 a and 146 b are shown inFIGS. 12 and 13. Referring to FIG. 12, a quartz bump 146 a is shownwhich is caused by foreign particles inhibiting proper etching asdescribed in the prior art or unbalanced chemical formulation of thephotoresist which causes a residual resist to remain on phase shiftlayer 124 after development and before etching. The residual resist isthen transferred into phase shift layer 124 after the etching ofsubstrate 122. FIG. 13 shows an incomplete quartz etch 146 b which iscaused by an inaccurate exposure, foreign particle or residual resist.FIG. 14 depicts a two-dimensional graphical representation of theincomplete quartz etch defect 146 b shown in FIG. 13.

Once phase shift defects 146 are discovered in mask 120, it is importantthat the size and dimensions of phase shift defects are analyzed toensure a precise repair is done to produce an accurate mask 120. In oneembodiment of the present invention, the analysis of the phase shiftdefects is performed by positioning mask 120 within an atomic forcemicroscope (AFM), not shown. The AFM is then positioned over a phaseshift defect utilizing the location data determined by the appearancetester. The AFM is then activated to precisely scan or measure the sizeand dimensions of phase shift defect 146. The AFM utilizes the dataobtained in the scan to generate a three-dimensional representation ofphase shift defect 146. FIG. 15 depicts a three-dimensional graphicalrepresentation of incomplete quartz etch 146 b generated by an AFM.Alternatively, a profilometer, for example a Dektak profilometerproduced by Veeco Instruments, Inc. of Plainview, N.Y., ananoprofilometer produced by Surface Interface, Inc. of Sunnyvale,Calif., or other similar device known in the art, may be implemented tothree-dimensionally analyze phase shift defects 146. By obtaining adetailed defect topograph, the present invention does not solely rely onthe FIB device to analyze the defect, thus being able to achieve anexact correction of the defect.

Once phase shift defect 146 is accurately and precisely analyzed andmeasured, mask 120 is then corrected or repaired by removing phase shiftdefect 146 and planarizing the repaired area. Phase shift defect 146 isremoved by directing actinic radiation at phase shift defect to sputterphase shift defect 146. In one embodiment of the present invention theactinic radiation is generated by a focus ion beam (FIB) device. Oneexample of an FIB device which is utilized to implement the presentinvention is an FIB device which outputs approximately 20-50 kV Gallium(Ga) ions, such as an SMI 9800 or SIR series manufactured by SeikoInstruments Inc. of Chibaken, Japan. Alternatively, an FIB deviceoutputting Gold (Au), Silicon (Si), Beryllium (Be), Indium (In), or Zinc(Zn) ions may also be used. The three-dimensional data or resultsgenerated by the AFM is forwarded to the FIB device. The FIB device thenproduces an etch map 156 (shown in FIG. 16) which defines exposureduration, beam scan location and drift correction for precise beam focuslocations. Mask 120 is positioned within the FIB device such that an FIB128 generated by the FIB device is directed at phase shift defect 146 tosputter or evaporate phase shift defect 146 thus producing a repairedand accurate mask 120.

Knowledge of the actinic radiation beam or FIB's etching shape andetching rate enhances the precision of the mask repair. In oneembodiment, compensation for actinic radiation beam parameters areincluded within calculations to generate etch map 156. Other parametersthat are used in various embodiments to provide further precisioninclude beam shape and sputter rate. In such embodiments, FIB 128parameters are taken into account in determining duration and intensityof FIB 128 exposure when FIB 128 is directed at phase shift defect 146,thus compensating for differing beam characteristics and thus ensuringaccurate repair of mask 120. Thus, FIB 128 is controlled by both thethree-dimensional results obtained from the analysis of defect 146 andthe FIB parameters.

Referring to FIG. 17, in one embodiment an actinic radiation or FIBdevice is used to sputter or generate predetermined test or measurementpatterns 162 and 164 into a test substrate material 160. Test substratematerial 160 will consist of the same quartz substrate material used toform the mask phase shift layer 124 (FIG. 9). Referring to FIG. 18, theactinic radiation or FIB test patterns 162 and 164 are then analyzed ormeasured to determine the FIB beam parameters including etch depth/dose168 a and 168 b, beam width/dose 170 a and 170 b, dose to aspect ratioand dose to pixel width. The parameters are then stored for use incalculating etching map 156 (see FIG. 16). In one embodiment of thepresent invention an AFM, a profilometer or other device well know inthe art is used to three-dimensionally measure the etched test patterns162 and 164, and produce three-dimensional results. The measured dataincluding the etch depth/dose 168 a and 168 b and the beam width/dose170 a and 170 b are forwarded to the FIB device, via a LAN, RS232C orother mechanism, and stored in an internal memory.

Using internal algorithms the FIB device creates etch map 156 utilizingthe three-dimensional data of phase shift defect 146 and FIB beamparameters. FIG. 16 depicts the etch map 156 of phase defect 146 b. Etchmap 156 is generated to accurately determine and define etch depth perdose area (depth/dose) and etch width/dose to accurately determining andminimizing the scan area according to the beam shape. Thus preventingthe beam from scanning an area larger than the actual defect area.

In an alternative embodiment, the appearance tester and the AFM arecoupled to a processor and memory. The defect location information andthree-dimensional results are forwarded from the appearance tester andAFM to the memory. The processor accesses the memory for the defectlocation information to control the AFM and FIB positioning. Further,the processor generates or calculates etch map 156 from the defectlocation information and the three-dimensional results. The etch map 156is forward from the processor to the FIB device. Alternatively, theprocessor utilizes the etch map 156 to provide control to the FIBdevice.

Mask 120 is then positioned in the FIB device and under FIB 128utilizing the defect location data determined by the appearance testerwhen mask 120 was analyzed for defects. Once accurately positioned, FIB128 is then activated according to the etching parameters and etch map156 to correct and planarize phase shift defect 146. Because therelationship between the dose and etching rates are accuratelyunderstood, etch map 156 is accurately generated to provide for aprecise dose for a specific height. Thus avoiding overetching andresulting in a repaired and accurate mask 120, shown in FIG. 19. In oneembodiment, mask 120 is exposed to Halogen gas while FIB 128 isactivated to repair mask 120 thus reducing the residual ionicimplantation in phase shift layer 124 and substrate 122 which reduces ornullifies loss of transmission. The Halogen gas is selected such thatthe FIB 128 will react with the etching gas thus reducing stainingeffects of the beam. Further, residual staining is eliminated bycleaning mask 120 following the repairing of defects 146. The cleaningincludes exposing the repaired area to a etchant capable of removing theFIB stains, for example hydrofluoric acids or heated alkali solutions asis known in the art.

FIG. 20 depicts a flow-chart of one embodiment of the method ofcorrecting a Levenson quartz engraving phase shift photomask. In step302 the etched mask 120 is analyzed for defects. Mask 120 is positionedin an appearance tester, wherein the appearance tester scans mask 120for defects. The process then proceeds to condition 304 where it isdetermined whether defects were found in mask 120. If defects 146 arenot found, then the process proceeds directly to step 342 where theprocess is terminated. If defects 146 are found, then step 306 isentered. In step 306 the defect location is determined and stored. Incondition 308, it is determined if the FIB beam parameters, for the FIBdevice to be used to eliminate defect 146, are know. If the FIB beamparameters are known, then the process proceeds directly to step 320. IfFIB beam parameters are not known, then steps 312 and 314 are preformed.In step 312, FIB 128 is directed onto a quartz test substrate material160 which is the same material as that of phase shift layer 124 utilizedin mask 120. The FIB device is activated for predetermined time to etcha predetermined test patterns 162 and 164. In step 314, test substratematerial 160 is positioned into an AFM and is three-dimensionallyanalyzed. The three-dimensional information of test patterns 162 and 164are stored and forwarded to the FIB device providing the FIB device withthe FIB beam and etching parameters. The process then proceeds to step320.

In step 320 mask 120 is positioned in the AFM. In step 322, the AFM ispositioned over defect 146 and a three-dimensional analysis of defect146 is performed. The results are then stored and forwarded to the FIBdevice. In condition 324 it is determined if all defects on mask 120have been three-dimensionally analyzed by the AFM. If not, then theprocess returns to step 322 where AFM is positioned over a second defectfor analysis. If yes the process proceeds to step 326. In step 326, anetch map 156 is generated for each defect 146 found based on thethree-dimensional analysis results obtained in step 322 and the FIB beamparameters. In step 328 mask 120 is positioned in the FIB device. Mask120 is then positioned utilizing the defect location previouslydetermined such that FIB 128 will be directed onto defect 146. In step330 the FIB device is activated according to the etch map 156 and beamparameters for a period of time as calculated according to the etch map156. In condition 334, it is determined if the FIB device has completelyeliminated the defects according to the location of the defect, the beamparameters, the etch map 156 and the three-dimensional analysis results.If not, the process returns to step 328 where the mask is shifted andrepositioned under the FIB according to the etch map 156. The processthen returns to step 330 where the FIB is activated again according tothe etch map 156. If, in condition 334, it is determined that the FIBdevice has eliminated the defect, the process moves to step 338 wherethe process determines if all defects found on mask 120 have beeneliminated. If yes, then the process proceeds to step 342 where theprocess is terminated. If not, the process returns to step 328 where FIBis again positioned over a second defect 146 based on the defectlocation.

Referring to FIG. 21, in one embodiment of the invention a single phaseshift correction apparatus 420 is utilized to perform the phase shiftdefect correction. Apparatus 420 includes an means for scanning oranalyzing 422 the photomask 120 for defects. In one embodiment, meansfor scanning includes an appearance tester. Apparatus 420 stores thedefect location information in an internal memory 424. Once mask 120 isfully scanned and all defect locations are acquired, apparatus 420utilizes an internal means to three-dimensionally analyze 428 eachdefect and generates three-dimensional results characterizing eachdefect. In one embodiment means to three-dimensionally analyze 428includes an AFM. The three-dimensional results are further stored inmemory 424. Apparatus 420 includes a means for correcting or eliminating434 phase shift defects, implemented to repair mask 120. In oneembodiment, means for correcting 434 includes an FIB device to direct anFIB onto defect 146. Apparatus 420 further includes a processor means ormicroprocessor 438 coupled to means for scanning 422, means forthree-dimensionally analyzing 428 and means for correcting 434.Processor means 438 also couples to memory 424 such that processor means438 utilizes the three-dimensional results to generate an etch map 156and to control each of the components of apparatus 420. In oneembodiment, the processor means includes a computer.

While the present invention has been described with reference to a fewspecific embodiments, the description is illustrative of the inventionand is not to be construed as liming the invention. Variousmodifications may occur to those skilled in the art without departingfrom the true spirit and scope of the invention as defined by theappended claims.

What is claimed is:
 1. An apparatus for repairing defects on aphotomask, comprising: means for analyzing the photomask for defectscoupled to a memory such that a defect location on the mask is stored inmemory; means for three-dimensionally analyzing the defect coupled tothe memory to store three-dimensional results of the three-dimensionalanalysis; processor means coupled to the memory, the means foranalyzing, the means for three-dimensionally analyzing and a means forcorrecting the defect such that the processor controls the means foranalyzing, the means for three-dimensionally analyzing and the means forcorrecting based on the defect location and the three-dimensionalresults; and the means for correcting the defect coupled to theprocessor to receive control instructions to eliminate the defect. 2.The apparatus for repairing defects as claimed in claim 1, furthercomprising: means for generating test patterns coupled to the processorsuch that the processor controls the means for generating test patterns.3. The apparatus for repairing the defect as claimed in claim 2, furthercomprising: means for three-dimensionally analyzing the test patterncoupled to the means for processing such that the means for processingcontrols the means for three-dimensionally analyzing the test pattern;and the means for three-dimensionally analyzing the test patternscoupled to the memory to store the three-dimensional test patternresults.
 4. A method for repairing defects in a photomask, comprising:locating at least one defect in the photomask; analyzing the at leastone defect in the photomask in three-dimensions producingthree-dimensional results; directing an actinic radiation beam onto thedefect; and controlling the actinic radiation beam directed onto thedefect based on the three-dimensional results obtained in the step ofanalyzing the defect.
 5. The method for correcting defects in aphotomask as claimed in claim 4, further comprising: exposing thephotomask to Halogen gas during the step of directing an actinicradiation beam and the step of controlling the actinic radiation beam.6. The method for correcting defects in a photomask as claimed in claim4, wherein: the step of controlling the actinic radiation beam includescontrolling the actinic radiation beam based on actinic radiation beamparameters.
 7. The method for correcting defects in a photomask asclaimed in claim 6, wherein: the step of controlling the actinicradiation beam based on the actinic radiation beam parameters includes:generating at least one actinic radiation beam test pattern;three-dimensionally analyzing the test pattern producingthree-dimensional test pattern results; and determining the actinicradiation beam parameters from the test pattern results.
 8. The methodfor correcting defects in a photomask as claimed in claim 6, wherein:step of controlling the actinic radiation beam includes generating adose map.
 9. A method for correcting defects in a photomask, comprising:scanning the photomask for defects; determining a location of at leastone defect; three-dimensionally analyzing the defect to producethree-dimensional results; and directing an actinic radiation beam ontothe defect to eliminate the defect.
 10. The method of correcting adefect in the photomask as claimed in claim 9, wherein: the step ofdirecting the actinic radiation beam onto the defect includes:controlling the actinic radiation beam according to thethree-dimensional results obtained in the step of three-dimensionallyanalyzing the defect.
 11. The method of correcting a defect in thephotomask as claimed in claim 10, further comprising: generating a dosemap based on the three-dimensional results prior to the step ofdirecting the actinic radiation beam onto the defect.
 12. The method ofcorrecting a defect in the photomask as claimed in claim 11, wherein:the step of generating a dose map includes generating the dose map basedon actinic radiation beam parameters.
 13. The method of correcting adefect in the photomask as claimed in further comprising: determiningthe actinic radiation beam parameters prior to the step of directingactinic radiation onto the defect.
 14. The method of correcting a defectin the photomask as claimed in claim 13, wherein: the step ofdetermining the actinic radiation beam parameters includes: generatingat least one test pattern; and measuring the test pattern.
 15. Themethod of correcting a defect in the photomask as claimed in claim 14,wherein: the step of measuring the test pattern includesthree-dimensionally measuring the test pattern.
 16. The method ofcorrecting a defect in the photomask as claimed in claim 15, wherein:the step of measuring the test pattern includes utilizing an atomicforce microscope (AFM) to measure the test pattern.
 17. The method ofcorrecting a defect in the photomask as claimed in claim 15, wherein:the step of measuring the test pattern includes utilizing a profilometerto measure the test pattern.
 18. The method of correcting a defect inthe photomask as claimed in claim 9, wherein: the step ofthree-dimensionally analyzing the defect includes utilizing an AFM inperforming the three-dimensional analysis.
 19. The method of correctinga defect in the photomask as claimed in claim 9, wherein: the step ofthree-dimensionally analyzing the defect includes utilizing aprofilometer in performing the three-dimensional analysis.
 20. Themethod of correcting a defect in the photomask as claimed in claim 9,wherein: the step of directing the actinic radiation beam onto thedefect includes calculating an exposure duration and beam intensity. 21.The method of correcting a defect in the photomask as claimed in claim9, further comprising: repositioning the mask such that a second defectis positioned under the actinic radiation beam; and directing theactinic radiation beam onto the second defect to eliminate the seconddefect.